EP0149668B1 - Lightbeam responsive circuit with electromagnetic noise reduction circuit - Google Patents

Lightbeam responsive circuit with electromagnetic noise reduction circuit Download PDF

Info

Publication number
EP0149668B1
EP0149668B1 EP84902860A EP84902860A EP0149668B1 EP 0149668 B1 EP0149668 B1 EP 0149668B1 EP 84902860 A EP84902860 A EP 84902860A EP 84902860 A EP84902860 A EP 84902860A EP 0149668 B1 EP0149668 B1 EP 0149668B1
Authority
EP
European Patent Office
Prior art keywords
circuit
output
level
photodetector
circuit according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84902860A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0149668A1 (en
Inventor
Bruce M. Komadina
Vladeta D. Lazarevich
August H. Beining
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Co
Original Assignee
Hughes Aircraft Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hughes Aircraft Co filed Critical Hughes Aircraft Co
Publication of EP0149668A1 publication Critical patent/EP0149668A1/en
Application granted granted Critical
Publication of EP0149668B1 publication Critical patent/EP0149668B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/042—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means
    • G06F3/0421—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means by interrupting or reflecting a light beam, e.g. optical touch-screen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties

Definitions

  • This invention relates generally to detection circuits that can be used with optical touch panels and more particularly to a circuit which compensates for the noise signals created by ambient light variations and by electromagnetic interference.
  • the photodetectors sampling switches which are sequentially energized to sense whether or not there is anything, such as a finger, blocking one or more of the light beams.
  • the photodetector output circuit normally extends substantially along two edges of a circuit board, and therefore, can be subject to electromagnetic interference, from voltages, currents and radiation typically within the proximity of the touch panel housing.
  • the photodetectors are affected by variations in the ambient lighting conditions where the unit is located, and these may also adversely affect the operation of the unit.
  • a light beam responsive circuit having a noise interference reduction circuit comprising: at least one light emitting device and at least one photodetector arranged in pairs, each pair being disposed along a light beam path extending therebetween; a photodetector output circuit; switching means for successively coupling the outputs of said at least one photodetector'to said photodetector output circuit; an electromagnetic noise compensation pickup circuit extending generally coextensively with an electrically balanced with said photodetector output circuit; and circuit means including combining means for differentially combining the outputs from said photodetector output circuit and said electromagnetic noise compensation pickup circuit to substantially eliminate electromagnetic noise components present on the output signal of said photodetector output circuit.
  • the input from the photodetector circuit is preferably fed through a high pass filter circuit to substantially eliminate the relatively low frequency effects of the more slowly changing variations in ambient lighting; while transmitting the relatively higher frequency pulses produced by the gating of light impulses from selected successive photodetectors.
  • the differential amplifier may be provided with a diode in the feedback circuit so that the desired photodetected signal pulses of one polarity are amplified at high gain levels; whereas pulses of the opposite polarity-are not amplified, in accordance with the feedback characteristics of the diode.
  • hysteresis type output circuitry is used for the photodetected pulse sensing circuits, which only changes state when a change is encountered when going from a beam transmission to a beam interruption, or vice-versa, as successive pairs of light emitters and photodetectors are scanned across the face of the touch panel faceplate.
  • the invention provides significant reduction in sensitivity to ambient lighting noise and increased reliability as a result of noise compensation by a substantial elimination of the noise component from the photodetector output signal.
  • relatively inexpensive light emitting diodes and phototransistors may be employed to significantly reduce the overall cost of the touch panel.
  • Another advantage is that the higher attainable signal to noise ratio permits the use of smaller photoemitter and photodetector devices since it is not necessary to overpower the ambient light levels because the devices are capable of operating at a level below the intensity of the ambient light.
  • Fig. 1 is an overall view of a touch panel unit 12 which has a faceplate 14.
  • a series of photoemitters such as light emitting diodes are located for example, at one side 18 of the faceplate to direct beams of infrared light across the faceplate 14 to photodetectors such as phototransistors located at the opposite edge 20 of the faceplate 14.
  • an additional set of light emitting diodes may be provided to direct illumination from the lower edge 22 of the faceplate upwardly to phototransistors located at the upper edge 24 of the faceplate.
  • the pairs of light emitting diodes and phototransistors are energized sequentially to scan across the faceplate both in the horizontal direction and in the vertical direction such that they intersect to form a grid pattern.
  • the light from each light emitting diode is directed across the faceplate to impinge on the opposing phototransistors locating the coordinates of where a finger 26 may be pointing, for example, either to a switch point or a portion of a display.
  • the interruption of one or more of the beams in each direction serves to locate the position of the finger 26.
  • a set of four circuit boards 32, 34, 36 and 38 may serve to mount the light emitting diodes and the phototransistors, along with their associated electronic circuitry.
  • the opposing pairs of light emitting diodes and phototransistors are switched on and off concurrently, with sequential energization of the successive pairs of phototransistors and light emitting diodes serving-to scan across the- face of the faceplate in both the horozontal and vertical directions.
  • the output from the phototransistors may be connected in parallel to detection and processing circuits, with the particular phototransistor from which a pulse is being received being indentified by the timing of the switching circuitry which sequentially turns on the paired light emitting diodes and phototransistors.
  • a phototransistor 42 is shown connected by switch 44 to a phototransistor output lead 46.
  • a plurality of additional switches 48 are also shown, and are representative of a series of parallel semiconductor switches which sequentially gate a series of parallel phototransistors to their conducting states, simultaneously with the energization of the opposite paired light emitting diode 40 which directs light onto the phototransistors 42.
  • the sequential energization of the switch 44 and the many switches indicated at 48, and their precise timing, identifies for the system which phototransistor is generating (or not generating) an output pulse 52 of Fig. 3.
  • the current associated with this pulse 52 flows through the load resistor 49 which has one end connected to a reference voltage - V. This causes the voltage level at the end of the .load resistor 49 to rise producing the output pulse 52.
  • Fig. 3 shows an idealized positive going output pulse such as might be recovered from the phototransistor 42 when the beam is not interrupted.
  • the phototransistor output lead 46 extends a considerable distance across the printed circuit board, for example printed circuit boards 34 and 36 of Fig. 1, a great deal of electromagnetic noise is picked up and added to the phototransistor output signal.
  • the phototransistor signal 52 may be relatively small, in the order of ten to fifteen millivolts, while the noise signals 54 may be substantially greater and may for example be even 100 to 150 millivolts.
  • a differential operational amplifier 56 is used with the signal from the phototransistor output lead 46 fed through a high pass filter circuit, which includes load resistor 49, series capacitor 58 and resistor 60, to the negative (-) input terminal of the amplifier 56; and a compensating signal equivalent to the noise signal components picked up on the noise compensating pickup lead 62 is coupled to the positive (+) input terminal of operational amplifier 56 through a high pass filter circuit which includes load resistor 65 and series connected capacitor 64 and resistor 66.
  • the compensation pick-up lead 62 indicated schematically at 62 in Fig. 1 is a long electrical conductor extending for substantially the full length of the circuit boards 34 and 36, commensurate in extent with the phototransistor output circuit 46, as indicated at the left in Fig. 2.
  • the lead 62 can be in the form of a wire, a printed circuit, plating, planar etch, etc.
  • the end of the lead 62 has a load termination circuit 63 equivalent to a phototransistor 42 and a switch 48 coupled to it.
  • This equivalent load circuit 63 can be in the form of a capacitor and a diode connected in parallel with one another.
  • the noise signals picked up on lead 62 results in current flow through load resistor 65 which will be substantially the same as the electromagnetic noise signals on phototransistor output lead 46.
  • these two sets of noise signals will substantially cancel one another out, while leaving only the desired characteristics of the phototransistor output signal 52 to be amplified and shaped by the time it arrives at test point TP-2 as shown in Figs, and 6.
  • the high pass filter including series capacitor 58, and resistor 60 and the load resistors connected in shunt to the capacitor discriminates against the relatively slowly changing levels of ambient light which will be received by the photodiodes and which might otherwise vary the output signal from the operational amplifier 56.
  • the high pass filter would pass 4% of the signal at 400 cps (cycles per second), 40% at 2000 cps, and 90% at 6000 cps.
  • the circuit formed by capacitor 64, resistor 66, and load resistor 65 in the compensation pickup lead branch is equivalent to the high pass filter.
  • the diode When the signal received by the differential amplifier (-) input terminal is negative relative to a reference level, the diode is forward biased, the feedback resistance is very low, and the gain at the operational amplifier 56 is very low whereupon the negative input signal is not amplified.
  • the diode 72 is back biased raising the feedback resistance and the gain of the operational amplifier 56 whereupon the input signal is amplified.
  • a first test point designated TP-1 in Fig. 2, is the point at which noisy signals such as those shown in Fig. 4 may be observed.
  • the representative signal of GFig. 5 attest point TP-2 was clamped by diodes 75 and 77 (which do-not conduct negative pulse signals or signals of more than +0.7 volts such as might be caused by switching transients and noise) and was amplified by operational amplifiers 56 and 74.
  • the actual signal with some slight residual uncompensated noise is shown in Fig. 6.
  • the diode 75 also serves to provide a path of conduction when the feedback diode 72 is forward biased.
  • the resistor 79 connected to clamping diode 77 serves to terminate the input to the (+) terminal of operation amplifier 56 and to aid the circuit in coming up to operation when the power is turned on.
  • both of the operational amplifiers 56 and 74 as shown in Fig. 2 may, for example, be of the types known as TL072 or LS353 operational amplifiers, and which are available from a number of manufacturers.
  • the comparators 80 and 82 to be discussed below may, for example, be of type LM393.
  • the high and low voltages for the system may, by way of example but not limitation, be either the commonly available plus and minus five volts or plus and minus twelve volts. However it has been determined that the higher the voltages, within limits, the more effective the circuit becomes.
  • the comparators 80 and 82 each have one input terminal (-) connected to receive the amplified output pulse from operational amplifier 74 and the other input terminal (+) coupled to receive reference signals VREF-1 and VREF-2 respectively.
  • an output pulse from comparator 80 is fed to the D input terminal of flip-flop 76 after it . is processed and limited by the clamping diode 81 and pull up resistor 83.
  • the flip-flops 76 and 78 may, for example, be of the type LS74.
  • the output of comparator 82 is fed to the D input terminal of flip-flop 78 after it is processed and limited by clamping diode 85 and pullup resistor 87.
  • the hysteresis portion of the circuit of Fig. 2 which includes flip-flops 76 and 78 evaluates the pulse level on the output lines from comparators 80 and 82 during gate pulse or clock pulse LED and stores it as data depending upon the levels of the signals. For example if the levels of the signal on these two output lines are both -higher in amplitude than the reference voltages VREF-1 and VREF-2 ( noriinterrupted beam) such as at time t 1 in Fig. 6 or both lower in amplitude than the referenced voltages VREF-1 and VREF-2 (interrupted beam) such as attimet 3 that state of the data is stored in the flip-flops 76 and 78 and used as the output data Q and Q on output lines 92 and 94.
  • the reference voltages VREF-1 and VREF-2 noriinterrupted beam
  • a hysteresis circuit can be implemented with a single J-K flip-flop 98 such as an LS 109 in the manner illustrated in Fig. 7.
  • the output Q is low. If however the signal to the J andK inputs are both high the output Q is high. However if the signal of the J input is low and the signal to the K input is high the output signal Q remains in its stored state from the preceding beam. Moreover if the signal of the J input is high and the input signal to the K input is low the flip-flop cannot toggle and the output Q will remain in the same state it was in from the preceding beam.
  • Fig. 8 shows one type of circuit it is possible to use another type illustrated in Fig. 8 such as load resistors 100 and 102 coupled between the collector of each phototransistor 42 and in common to the lead 62.
  • the emitters of phototransistors 42 are switched to ground to select the desired beam.
  • These load resistors 100 and 102 would be tapped with a reference voltage +V: such as 5 volts, with the last load resistor tapped to ground.
  • the collectors of each of the phototransistors 42 are ganged to the lead 46 so that a negative going pulse is produced in response to an unblocked beam when the switches 48 are sequentially closed.
  • circuit of Fig. 2 has been described as generating and processing positive going phototransitor output pulses 52 it is possible to handle negative going output pulses 52 that would be produced by the circuit of Fig. 8 by reversing the polarity of clamping diodes 75 and 77 and feedback diode 72.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Electronic Switches (AREA)
  • Position Input By Displaying (AREA)
  • Optical Communication System (AREA)
  • Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)
  • Length Measuring Devices By Optical Means (AREA)
EP84902860A 1983-07-11 1984-06-29 Lightbeam responsive circuit with electromagnetic noise reduction circuit Expired EP0149668B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/512,821 US4591710A (en) 1983-07-11 1983-07-11 Ambient light and electromagnetic noise reduction circuit
US512821 1983-07-11

Publications (2)

Publication Number Publication Date
EP0149668A1 EP0149668A1 (en) 1985-07-31
EP0149668B1 true EP0149668B1 (en) 1987-12-02

Family

ID=24040720

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84902860A Expired EP0149668B1 (en) 1983-07-11 1984-06-29 Lightbeam responsive circuit with electromagnetic noise reduction circuit

Country Status (11)

Country Link
US (1) US4591710A (ja)
EP (1) EP0149668B1 (ja)
JP (1) JPS60501825A (ja)
KR (1) KR890004769B1 (ja)
AU (1) AU572536B2 (ja)
CA (1) CA1220829A (ja)
DE (1) DE3467944D1 (ja)
ES (1) ES534167A0 (ja)
IL (1) IL72296A (ja)
IT (1) IT1179391B (ja)
WO (1) WO1985000682A1 (ja)

Families Citing this family (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4712003A (en) * 1983-07-27 1987-12-08 Itsuki Ban Blind person guide device
US4710759A (en) * 1984-02-22 1987-12-01 Zenith Electronics Corporation Interactive CRT with touch level set
US4943806A (en) * 1984-06-18 1990-07-24 Carroll Touch Inc. Touch input device having digital ambient light sampling
US4695827A (en) * 1984-11-20 1987-09-22 Hughes Aircraft Company Electromagnetic energy interference seal for light beam touch panels
JPH0337062Y2 (ja) * 1985-05-17 1991-08-06
WO1987002846A1 (en) * 1985-10-29 1987-05-07 Hopper William R Touch sensitive indicating light
US4799044A (en) * 1986-02-18 1989-01-17 Amp Incorporated Phototransistor apparatus with current injection ambient compensation
US4684801A (en) * 1986-02-28 1987-08-04 Carroll Touch Inc. Signal preconditioning for touch entry device
US4893120A (en) * 1986-11-26 1990-01-09 Digital Electronics Corporation Touch panel using modulated light
US4845479A (en) * 1986-12-22 1989-07-04 Xerox Corporation High reliability PWB interconnection for touch input systems
US4818859A (en) * 1987-06-01 1989-04-04 Carroll Touch Inc. Low profile opto-device assembly with specific optoelectronic lead mount
US4855590A (en) * 1987-06-25 1989-08-08 Amp Incorporated Infrared touch input device having ambient compensation
US5164714A (en) * 1988-06-20 1992-11-17 Amp Incorporated Modulated touch entry system and method with synchronous detection
US4988983A (en) * 1988-09-02 1991-01-29 Carroll Touch, Incorporated Touch entry system with ambient compensation and programmable amplification
US5113068A (en) * 1990-12-28 1992-05-12 Square D Company Photoelectrical sensor with multistaged, filtered amplifier circuit
US5378069A (en) * 1992-08-24 1995-01-03 Product Engineering & Mfg., Inc. Environmentally safe touch typing keyboard
US5577848A (en) * 1992-08-24 1996-11-26 Bowen; James H. Light controlled touch pad for cursor and selection control on a computer display
US5605406A (en) * 1992-08-24 1997-02-25 Bowen; James H. Computer input devices with light activated switches and light emitter protection
US5508521A (en) * 1994-12-05 1996-04-16 Cardiovascular Diagnostics Inc. Method and apparatus for detecting liquid presence on a reflecting surface using modulated light
US6256157B1 (en) 1998-05-15 2001-07-03 International Business Machines Corporation Method and apparatus for removing noise spikes
WO2005029394A2 (en) * 2003-09-22 2005-03-31 Koninklijke Philips Electronics N.V. Light guide touch screen
US7995036B2 (en) 2004-02-27 2011-08-09 N-Trig Ltd. Noise reduction in digitizer system
JP4550712B2 (ja) * 2005-10-17 2010-09-22 ルネサスエレクトロニクス株式会社 受光回路
KR101593574B1 (ko) 2008-08-07 2016-02-18 랩트 아이피 리미티드 광학 터치 감응 장치에서 멀티터치 이벤트를 감지하는 방법 및 기구
US9092092B2 (en) 2008-08-07 2015-07-28 Rapt Ip Limited Detecting multitouch events in an optical touch-sensitive device using touch event templates
JP5345007B2 (ja) * 2009-06-29 2013-11-20 株式会社ワコム 位置検出装置、位置検出回路及び位置検出方法
US9052778B2 (en) * 2009-12-16 2015-06-09 Beijing Irtouch Systems Co., Ltd Infrared touch screen
US8836672B2 (en) 2011-02-09 2014-09-16 Dornerworks, Ltd. System and method for improving machine vision in the presence of ambient light
TWI497376B (zh) 2011-07-22 2015-08-21 Rapt Ip Ltd 在光學觸敏裝置中使用之光學耦合器總成
US9524060B2 (en) 2012-07-13 2016-12-20 Rapt Ip Limited Low power operation of an optical touch-sensitive device for detecting multitouch events
US10095361B2 (en) 2015-03-18 2018-10-09 Microsoft Technology Licensing, Llc Stylus detection with capacitive based digitizer sensor
US10296146B2 (en) 2015-12-22 2019-05-21 Microsoft Technology Licensing, Llc System and method for detecting grip of a touch enabled device
US10423268B2 (en) 2015-12-22 2019-09-24 Microsoft Technology Licensing, Llc System and method for detecting grounding state of a touch enabled computing device
US9823774B2 (en) 2016-02-23 2017-11-21 Microsoft Technology Licensing, Llc Noise reduction in a digitizer system
US10678348B2 (en) 2018-03-12 2020-06-09 Microsoft Technology Licensing, Llc Touch detection on an ungrounded pen enabled device
US10616349B2 (en) 2018-05-01 2020-04-07 Microsoft Technology Licensing, Llc Hybrid sensor centric recommendation engine
US11536589B2 (en) * 2021-03-09 2022-12-27 Toyota Motor Engineering & Manufacturing North America, Inc. Electromagnetic noise position sensing
CN114594494B (zh) * 2022-01-13 2022-10-21 杭州宏景智驾科技有限公司 激光雷达系统及其环境光去噪方法
CN117079975B (zh) * 2023-07-28 2024-04-30 厦门亿芯源半导体科技有限公司 高速tia抗5g wifi电磁干扰方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4198623A (en) * 1978-11-13 1980-04-15 Sanders Associates, Inc. Touch entry interactive cathode ray tube arrangement
US4243879A (en) * 1978-04-24 1981-01-06 Carroll Manufacturing Corporation Touch panel with ambient light sampling

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3576452A (en) * 1968-05-28 1971-04-27 Motorola Inc Photodiode preamplifier circuit for a card reader system
US4384201A (en) * 1978-04-24 1983-05-17 Carroll Manufacturing Corporation Three-dimensional protective interlock apparatus
US4335316A (en) * 1980-04-09 1982-06-15 Baldwin-Korthe Web Controls, Inc. Web break detector with adjustable scanning head

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4243879A (en) * 1978-04-24 1981-01-06 Carroll Manufacturing Corporation Touch panel with ambient light sampling
US4198623A (en) * 1978-11-13 1980-04-15 Sanders Associates, Inc. Touch entry interactive cathode ray tube arrangement

Also Published As

Publication number Publication date
IT1179391B (it) 1987-09-16
ES8603666A1 (es) 1985-12-16
IL72296A0 (en) 1984-11-30
IT8448530A0 (it) 1984-07-09
CA1220829A (en) 1987-04-21
ES534167A0 (es) 1985-12-16
US4591710A (en) 1986-05-27
WO1985000682A1 (en) 1985-02-14
AU572536B2 (en) 1988-05-12
AU3152784A (en) 1985-03-04
JPS633333B2 (ja) 1988-01-22
KR890004769B1 (ko) 1989-11-25
KR850001590A (ko) 1985-03-30
JPS60501825A (ja) 1985-10-24
IL72296A (en) 1987-10-20
DE3467944D1 (en) 1988-01-14
EP0149668A1 (en) 1985-07-31

Similar Documents

Publication Publication Date Title
EP0149668B1 (en) Lightbeam responsive circuit with electromagnetic noise reduction circuit
US5414413A (en) Touch panel apparatus
US3999060A (en) Device for receiver for optical signals
US5994689A (en) Photoelectric cell with stabilised amplification
US4808809A (en) Device for optically detecting the presence or absence of an object on an optical path including a variable I-V characteristic circuit to effect in a positive feedback relationship between the radiation source and the radiation detector
US11625128B2 (en) Optical touch sensor systems and optical detectors with noise mitigation
CA1073056A (en) Optical pulse transmission system
EP0567934B1 (en) Video signal processor employing edge replacement, preshoots and overshoots for transient enhancement
US4615616A (en) Measuring distance apparatus
US5296697A (en) Detection circuit for maintaining constant signal transfer characteristics of a light-sensitive detector
EP0304560B1 (en) Photodetector having cascaded photoelements
US3668659A (en) Touch-wire detection systems
US3835400A (en) Sequential automatic gain control circuit
JP4318762B2 (ja) ロック可能な差分処理を行う光電セル
US4801797A (en) Optical position input device
CN108847896A (zh) 红外触控屏光信号接收电路
GB2181234A (en) Two-dimensional ink drop position detecting apparatus
US4319133A (en) Photoelectric detection system
EP0340393A2 (en) Position detecting circuit
CN113805244B (zh) 一种微型激光探测装置及其控制方法
JPH08272537A (ja) 光学式タッチパネル
JPH04247761A (ja) 同期検出回路
JPH024033A (ja) 光受信器
US4698528A (en) Edge detection using dual trans-impedance amplifier
JPH06104460A (ja) 光検出装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19850220

AK Designated contracting states

Designated state(s): CH DE FR GB LI NL SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: HUGHES AIRCRAFT COMPANY

17Q First examination report despatched

Effective date: 19860915

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): CH DE FR GB LI NL SE

REF Corresponds to:

Ref document number: 3467944

Country of ref document: DE

Date of ref document: 19880114

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19940517

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19940520

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19940630

Year of fee payment: 11

EAL Se: european patent in force in sweden

Ref document number: 84902860.0

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19950630

Ref country code: LI

Effective date: 19950630

Ref country code: CH

Effective date: 19950630

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19960101

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 19960101

EUG Se: european patent has lapsed

Ref document number: 84902860.0

REG Reference to a national code

Ref country code: GB

Ref legal event code: 732E

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20030512

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20030516

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20030527

Year of fee payment: 20

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20040628

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20